It is known that addition of an organic acid to a lower alcohol such as ethanol enhances a microbicidal activity of ethanol preparations for food preservation.
For example, the patent literatures 1 and 2 individually disclose ethanol preparations for food preservation comprising ethanol, and an organic acid or a salt thereof, etc. The patent literatures 3 and 4 individually describe that microbicides comprising an alcohol such as ethanol and an organic acid can be used for hand wash and hand disinfection. The patent literature 5 discloses a sanitizing hand cleanser that can be used without water, comprising about 60 to 90% by weight of an organic alcohol, about 5 to 35% by weight of one or more silicone-based materials, about 5% by weight or less of one or more humectants, about 12% by weight or less of one or more additives for maintaining the skin pH, and one or more thickeners at such a concentration that the viscosity of the cleanser is within the range of 100 to 10,000 cp at about 25° C. The patent literature 6 discloses an alcohol preparation for reducing a population of microorganisms at low temperature, which is used for refrigerated or frozen foods, etc. and which comprises ethyl alcohol and phytic acid as essential ingredients.
Such ethanol preparations have a microbicidal activity, but the above literatures do not teach the activity of the preparations against viruses.
The patent literature 7 describes a method for disinfection, comprising contact with a 0.05 to 3% by weight aqueous solution of citric acid to inactivate a hepatitis virus B. In this method, lactic acid, malic acid and/or tartaric acid may be further added to the above solution. The patent literature 8 discloses a broad spectrum virucide comprising at least 70% by weight of ethanol and/or propanol, and 0.5 to 5% by weight of a short chain organic acid. The virucide in question has a short chain organic acid especially with 2 to 6 carbon atoms and is effective against a wide range of viruses, such as polioviruses, vaccinia viruses, SV40-viruses and adenoviruses. The literature also describes that this virucide can be used for hand disinfection as an example of its application.
The patent literature 9 discloses a virucidal disinfectant comprising an effective amount of a salt of metals belonging to alkali metals, alkaline earth metals, earth metals, and/or metals of the first, second or third secondary group of the periodic system of elements (transition element), in the form of an aqueous or alcoholic solution. In the Examples, the disinfectant was examined for its effectiveness against polioviruses, adenoviruses, vaccinia viruses and SV40 tumor viruses. The patent literature 10 discloses a method for reducing a population of a microorganism, comprising contact, at 5° C. or lower, with an aqueous alcoholic salt solution comprising 70 to 80 wt % alcohol; an alkali metal, an alkaline earth metal, zinc or a mixture thereof; a chloride or a phosphate; and the like, and the method reportedly showed a virucidal effect against adenoviruses etc., below the freezing point.
However, the virucides according to the patent literatures 7 to 10 are not satisfying enough to provide a fast-acting and persistent effect.
The patent literature 11 discloses a composition comprising (a) a divalent zinc salt as an essential ingredient, and optionally (b) an disinfecting alcohol, (c) an antimicrobial agent, and (d) an organic acid, wherein the composition has a pH of 5. This literature also discloses a method for reducing a bacteria and virus population, comprising contacting hands etc. with the composition for 30 seconds to achieve a log reduction of at least 4 against an acid-labile virus. The patent literature 12 discloses an anti-irritant composition comprising two or more water-soluble organic salts of zinc at concentrations of 0.1 to 2% (w/w), wherein the anti-irritant composition further comprises water, an alcohol and one or more agents selected from the group consisting of a gelling agent, a thickener, a hydrophilic or hydrophobic polymer, an emulsifier and an emollient. However, the composition according to the patent literature 11 or 12 also has room for improvement of its fast-acting and persistent effect.
The patent literature 13 discloses a pre-surgical disinfecting composition comprising a C1-6 alcohol in an amount of at least about 50 mass % based on the total mass of the disinfecting composition; an acid selected from an inorganic acid, an organic acid and a mixture thereof; and a cationic oligomer or polymer, wherein the composition provides a log kill of greater than about 3 in less than about 3 minutes against resident and transient skin flora. The patent literature 13 also discloses that the composition may further comprise a transition metal compound such as a zinc compound as an auxiliary antimicrobial agent. However, this composition also has room for improvement of its fast-acting effect.    Patent Literature 1: JP-A 3-168075    Patent Literature 2: JP-A 63-22171    Patent Literature 3: JP-A 11-5734    Patent Literature 4: JP-A 2002-253188    Patent Literature 5: JP-A 2004-107667    Patent Literature 6: JP-A 7-298862    Patent Literature 7: JP-B 3761199    Patent Literature 8: JP-A 63-14702    Patent Literature 9: JP-W 7-504175    Patent Literature 10: U.S. Pat. No. 6,551,553    Patent Literature 11: WO2006/062845    Patent Literature 12: JP-W 2005-524634    Patent Literature 13: JP-A 2007-211012